Apparatus for quenching ring gears and similar articles



Filed May 5, 1954 July 14, 1959 H. J. GREGG 2,

APPARATUS FOR QUENCHING RING GEARS AND SIMILAR ARTICLES 5 Sheets-Sheet 1 FIG.I

. INVENTOR: HENDRICK J. GR GG July 14, 1959 GREGG 2,894,519

APPARATUS FOR QUENCHING RING GEARS AND SIMILAR ARTICLES Filed May 5, 1954 5 Sheets-Sheet 2 FIG. 2

INVENTOR. HENDRIGK J. GREGG ATT'YS ,July 14, 19.59 H. J. GREGG 2,894,519

APPARATUS FOR QUENCHING RING GEARS AND SIMILAR ARTICLES Filed May 5, 1954 5 Sheets-Sheet s POSITION INVENTOR: HENDRICK J. GREGG BY I I FIG. 3

y 14, 1959 I H. J. GREGG 2,894,519

APPARATUS FOR QUENCHING RING GEARS AND SiMILAR ARTICLES Filed May 5, 1954 5 sheets-sheet 4 kill l7 l6 2| '5 IN VEN TOR! HENDRICK J. GREGG BY 41! I ATT'YS y 1959 H. J. GREGG 2,894,519

I APPARATUS FOR QUENCHING RING GEARS AND SIMILAR ARTICLES Filed May 5. 1954 5 Sheets-Sheet 5 FIGS INVENTOR. HENDRICK J. G EGG A ATT'YS United States Patet APPARATUS FOR QUENCHING RING GEARS AND SIMILAR ARTICLES Hendrick J. Gregg, Arlington Heights, Ill.

Application May '5, 1954, Serial No. 427,7 89

8 Claims. (Cl. 134-147) This invention relates generally to apparatus for quenching particularly adapted for use in quenching hot pieces of metal such as large tractor and automotive ring gears, large size bearing races and other generally circular or annular work pieces or gears, or the like, especially those which in normal use rotate about an axis and which usually require press quenching.

The present invention relates to improvements on the inventions described and claimed in my copending applications Serial Nos. 22,793, filed April 23, 1948, which matured into US. Patent 2,684,073 on July 20, 1954, and Serial No. 378,822, filed September 8, 1953, later abandoned.

The process of quenching items like those mentioned above has heretofore requiredpresses which include elaborate and expensive dies to control the distortion of the work pieces and usually only one work piece is quenched at a time. The quench media is generally oil which is maintained at a temperature between 110 F. to 130 F. and the machine must be connected to elaborate auxiliary cooling, conditioning, storage, pump and piping facilities.

The quenching involved in the present invention relates to the art of what is commercially known as martempering. The invention is applicable to the quenching of a single work piece and can also be employed in quenching aplurality of workpieces at the same time.

One of the objects of the invention is to provide a new and improved apparatus for quenching hot pieces of material such as ring gears, and the like, which will minimize warpage or distortion and produce a high quality gear economically.

Another object of the invention is to provide apparatus for quenching characterized by the employment of variable agitation and the location of an agitator underneath the hot gear or other work piece to be quenched.

An additional object of the invention is to provide a new and improved apparatus for quenching characterized by variable speed of rotation of the work piece.

Still a further object of the invention is to provide a new and improved apparatus for quenching hot work pieces, especially ring gears and the like, wherein the hot work piece is charged horizontally and quenched vertically.

An additional object of the invention is to provide apparatus of the type described characterized by a variable time cycle which can be adjusted for any given work piece to be quenched, for example, in order to compensate for heavy sections which require a longer quenching period.

Another object of the invention is to provide apparatus for quenching of the type described wherein the quenching medium is agitated only during the quenching cycle thereby avoiding harmful effects on the quenching medium, including physical and mechanical deterioration which sometimes is caused by excessive agitation.

- Another object of the invention is to provide a new and improved apparatus for heating and cooling an oil quenching medium. 7

A further object of the invention is to provide a new ice 2 and improved apparatus for clamping the workpiece before and during the quenching operation.

An additional object of the invention is to provide apparatus for clamping the work piece to be quenched which permits variable pressure of the clamp on the web of a ring gear or the like and avoids too tight a clamping pressure which would upset the metal.

Another object of the invention is to provide apparatus for quenching which is especially useful in quenching spiral, bevel or hypoid automotive ring gears.

Another object of the invention is to provide a'new and improved apparatus for quenching characterized by the fact that the work piece emerges from the bath before it stops rotating thereby providing a wiping a'c'tion effective to remove a substantial part of the quenching media.

Other objects and advantages of the invention will be apparent by reference to the following description in'con junction with the accompanying drawings in which:

Fig. 1 is a side elevational view partly in section of one form of a quench machine provided in accordance with the invention;

Fig. 2 is a top plan view with parts broken away taken along the line 1-1 of Fig. 1;

Fig. 3 is a front elevational view with parts broken away and partly in section of the machine shown in Fig. '1;

Fig. 4 is a sectional side elevational view illustrating particularly the heating and cooling mechanism for the quenching medium;

Fig. 5 is a sectional view taken along the line 5-'-"5 of Fig. 2 of the clamping device adapted to hold a ring gear or other similar work piece in place for the quench ing operation;

Fig. 6 is a partial sectional view taken along the line 6-6 of Fig. 5;

Fig. 7 illustrates the wiring diagram of the apparatus; and Fig. 8 illustrates hypoid gears for the quenching of which the invention is particularly well adapted.

Briefly described, the invention involves the employ ment of a generous sized tank which is adapted to contain a volume of a quenching medium which may a special salt bath or a mar-quenching oil. In mar-quenching, a hot carburized gear is taken from the furnace at a tem* perature around 1600 F to 1650 F. fully austenized and quenched by quickly cooling the gear to say 800 F. so as to retain the austenitic structure. Because marten'site does not form for the usual gear steels (SAE 4620, SAE 8620, SAE 50B20, SAE 51B20) until say 450 F., the temperature of the mass sections is equalized to a uniform temperature of around 400 F. in the quenching machine; The gear is then removed from the machine when the actual transformation to martensite is done in the open atmosphere. By this method internal strains are greatly reduced yet full metallurgical treatment is accomplished; The resultant gears have excellent physical characteristics and have a much longer life and are stronger than the same gears made from the same steels and quenched by conventional methods wherein a hot carburized gear is placed in a press and held in close die tooling under pres sure and then treated with a controlled amount of quench oil.

In the present invention the quenching tank is wholly devoid of the conventional external auxiliary coolers, pumps, storage tank and piping facilities. The novel form of heating and cooling and the agitation means PTO.- vided in accordance with the invention, as morefully 'described hereinafter, are so arranged to maintain the bath at the proper temperature, this temperature usually being within the range of from 375 F. to 400 F.

One or more rotatably mounted spindles are provided onto which the hot gear or other work piece is charged.

3 A feature of the present invention is that the gear to be quenched can be charged in a horizontal position.

Another feature of the invention is that the gear is clamped by means of a rotating air cylinder which permits variable pressure on the web of the gear. This is important because too great a pressure or a clamping mechanism which is too tight tends to upset the metal and produce harmful effects on the physical properties of the gear.

The gear or hot work piece clamped on the spindle rotates and moves downwardly during rotation into the quench bath. A feature of the invention is that the gear moves from a horizontal charging position to a vertical quenching position. Improved results are obtained by rotating the gear vertically during quenching as compared with rotating it horizontally. At the same time the invention provides for charging the gear in the horizontal position which is much simpler and more convenient in practical operation. After quenching for a predetermined period of time, which will depend upon the article being quenched, the spindle carrying the gear or other work piece is automatically elevated to a position where the gear or other work piece can be removed.

In the practice of the invention it has been found that controlled agitation is very important and one feature of the invention which contributes to the improved results obtained is the location of an agitator directly beneath the work piece which is being quenched. This agitator can be mounted on the same carriage which carries the article to be quenched, as hereinafter described in conjunction with the drawings. This insures that the agitator and the work piece always occupy the same relative positions during the quenching cycle. An optional but less desirable construction is to locate the agitator below the article to be quenched, for example, on the bottom of the tank containing the quenching medium but not mounted on the same carriage as the work piece.

The invention provides for a variable speed drive of the agitator mounted underneath the work piece. It also provides for a variable speed drive for the spindle which rotates the work piece. The invention further provides for a variable time cycle to permit the immersion of the work piece in the quenching medium for different periods of time depending upon the size of the work piece and the amount of quenching desired.

- A further feature of the invention is that the agitator operates only during the quenching cycle and thereby avoids destructive deterioration of a quenching medium such as oil which is adversely affected by too much agitation.

. Improved means are provided in the practice of the invention for heating and cooling the quenching medium whereby the temperature of the quenching medium can be carefully controlled.

Another feature of the invention is that as the work piece is elevated prior to emergence from the bath it changes from a vertically rotating position to a horizotally rotating position and continues to rotate horizo'ntally as it emerges from the bath thereby removing the quenching medium by centrifugal action and throwing it outwardly against the sidewalls of the tank and back into the bath. The horizontal rotation of the spindle above the liquid level makes a hood unnecessary although one may be provided as a precautionary measure.

Referring now more particularly to the drawings, one of the preferred forms of apparatus used in the practice of. the invention includes a tank generally indicated by the numeral 1. A superstructure or frame 2 is built as a part of the machine and extends above the tank 1.

The tank 1 includes a bottom 3, ends 4, 4 and sides 5, 5. The heating and cooling means includes one or more pipes or conduits 6 each of which extends downwardly into the tank 1 and is so constructed that one end 7 thereof extends above the tank and the other end 8 4 extends through the side walls of the tank in a lower portion thereof. The end 8 of pipe 6 is connected to a burner generally indicated .at 9 which supplies heated air or gases to the pipe 6; The end 7 of the pipe 6 is connected to an eductor generally indicated at 10 which is utilized for drawing air through the pipe 6. The heated gases in the pipe 6 heat the quench medium 11. The embodiment of the invention disclosed herein illustrates three of these pipes 6 but it will be evident that the number of these pipes is not an important consideration so long as the design is such that the temperature of the quench medium can be properly and accurately controlled within certain predetermined The temperature control is facilitated by passing air or other cooling fluid through the inlet opening 12 to a blower 13 and through the outlet opening 14 into a passageway 15. The passageway 15 is connected to a passageway 16 which is provided with a bafie 17 that directs the gases flom the blower 13 along the bottom of the tank 1 and into the passageway'ls around the sides, ends and bottom of the tank. These gases emerge through the openings 19.

The upright frame 2 consists of a pair of upright members 2t), 20 each preferably being formed from a pair of U-shaped structural steel girders and each being rigidly secured to a girder 21 at the bottom of the apparatus and to a girder 22 at the top of tank 1. 1

The structural members 20, 20 extend upwardly at th rear of the tank a considerable distance beyond the top of the tank and have the function not only of providing a support for the superstructure 23 but also of providing tracks for guiding the carriages 24 in their vertical reciprocating movement. The carriages 24 are mounted on the structural members 20, 20 by means of wheels 25 carried on axles 26. The apparatus illustrated in the drawing provides for two reciprocating carriages 24 but it will be understood that the machine can be provided with only one such carriage or a number greater than two.

Each of the carriages 24 has mounted thereon an electric motor 27 or other suitable driving mechanism which is connected through driving means 28 by pulleys and belts or in any other suitable manner to variable transmission 29. The drive shaft 31 drives the shaft 32 through a chain and sprocket driving means generally indicated at 33. The drive shaft is connected to a Western gear shaft box 34 through which it drives shaft 35, the latter in turn being drivingly connected to shaft 36 through suitable bevel gears in box 37. Drive shaft 36 drives marine propeller agitator 38 through a chain and sprocket and driving mechanism generally indicated at 39.

The shaft 32 drives a worm gear 40 which in turn drives a pinion 41 secured to a tubular shaft or sleeve 42. Sleeve 42 rotates in bearings 43 and 44 carried by arms 45 and 46, respectively. The sleeve shaft 42 is threadedly secured at 47 to a member 48 which in turn is secured by means of machine screws 49 or in some other suitable Y manner to supporting plate 50 carrying a gear or other work piece 51. The supporting plate 50 preferably contains radially extending grooves 52. The inner guide ring 53, slightly smaller than the inner diameter of the gear to be quenched, is fastened to supporting plate 50 by machine screws 54 or in any other suitable manner.

The clamping member generally indicated at 55 has outwardly extending arms 56 which clamp the inner skirt 57 of the gear against the supporting plate 50. The clamping member 55 is detachably mounted on the end of shaft 58 and secured thereto by a fastening device 59 as shown in Figs. 5 and 6 which consists of projecting elements 60 adapted to overlie and engage other projecting elements61 on clamping member 55. The elements 60 are spaced from each other by a space 62 a distance slightly greater than the width of the elements 61. Thus, a slight rotation of the clamping member 55 will align the element 61 with the space 62 and permit removal of the clamping member 55'. Conversely, when a gear 51 is charged on to mounting plate "50 the clamping member 55 can be placed over the shaft58 and locked in place by rotating the'clamping member 55 a fraction of a turn.

Inasmuch as the work piece is very hotat the time it is charged, means are provided to apply the clamping member 55 to the shaft 58 at adistancefrom the Work piece. This is accomplished by making the shaft 58 axially movable in the sleeve 42 andconnecting it to a piston rod 63 which in turn is connected to a piston 64 mounted in a rotating air cylinder 65. Air-orother fluid introduced into the inlet opening 66 passes through passageway 67 and causes the piston 64 to move the piston rod 63 and the shaft 58, together with the associated clamping member 55, to the dotted line position shown in Fig. 5. The clamping member 55 is then removed from the end of shaft '58 in the manner previously described. The hot work piece is placed on mounting plate 50. The clamping member 55 is replaced. The flow of air through line 66 is discontinued and air or other fluid is introduced through line 68 and passageway 69 to the opposite side of piston 64 causing the piston rod 63 to be retracted together with the shaft 58 and the associated clamping member 55 until the latter clamps the inner skirt of the gear 51 against the supporting plate 50. This arrangement has the advantage that the fluid pressure which holds the gear 51 or other work piece in place canbe carefully controlled or regulated so as to avoid too much pressure against the gear that might tend to upset, warp or distort the metal from which the gear is made.

' In Fig. 3 the gear 51 is shown in the-position'it'occupies just prior to quenching and the gear 51 is shown in the quenching position. One of the features of the apparatus is the provision of a mechanism .for charging the gear in the horizontal position occupied by the gear 51 inFig. 3, starting the rotation of the gear in this position andthen immersing it in. the quenching medium while rotating it continuously during the immersion and thereafter continuing to rotate it in the substantial vertical position occupied by the gear 51 in Fig. 3., This isaccomplished by mounting the clamping mechanism which holds the gear on the shaft 32 with bearings integral to the carriage assembly 24 with agitator 38. As the carriage 24 lowers from horizontal gear charging position, the link 72 at pin 71 forces arm 70, integral to the clamp mechanism, downwardly, causing the clamp assembly to rotate and pivot on shaft 32 causing the gear 51, or other work piece, to take a vertical position of the gear 51.

At the same time the drive arrangement and the relative position of the driving elements remain fixed so that the worm gear 40 continues to drive the pinion 41 and rotate the gear or other work piece which is clamped in the supporting mechanism. 'It will be observed that the agitating propeller 38 which is mounted from the carriage 24 moves up and down in substantially fixed relation with the up and down movement of carriage 24 and hence the efiect of the agitation-on the rotating work piece is always substantially uniform. When the work piece is rotating around its horizontal axis in quenching position, the axis of rotation of the propeller 38 is substantially directly beneath the work piece and substantially at right angles to the axis of rotation of the work piece. Furthermore, the direction of agitation is directly toward the support carrying the work piece and the quenching bath can be regarded as flowing in lines parallel with respect to the base of the work piece. A grid 73 having spaced openings 74 is disposed between the agitating propeler 38 and the support carrying the work piece in order to produce parallel lines of flow and provide enhanced uniformity of flow and temperature control of the portion of the bath which is brought into direct contact with the work piece. The grid 73 also 6 Y serves as a guard to prevent objects from falling into the propeller 38.

The up and down movement of the carriage 24 is accomplished in any suitable manner and in the apparatus described herein this is accomplished by means of an-air cylinder 75 (Figs. 1 and 2) located between the upright girder members 20, 20. The air cylinder 75 is provided with a piston 76 connected to a piston rod 77 which in turn is connected to the underneath side of carriage 24 at point 78. Connections for compressed fluid to be admitted on opposite sides of piston 76 are indicated by the numerals 79 and 80. When compressed air or other compressed fluid is introduced through the opening 80, the piston 76 is forced upwardly until the support carrying the work piece is in the charging position or removal position shown in dotted lines in Figs. 1 and 4 and in full lines on the right hand side of Fig. 3. When the quenched work piece has been removed and another article to be quenched is charged on the support, air or other compressed fluid is admitted through the port 79 causing the piston 76 to move downwardly along with the carriage 24 to the position shown in full lines in Fig. 1 and on the left hand side of Fig. 3. The flow of compressed air to ports 79 and 80 is controlled by a solenoid valve generally indicated at 81 in Fig. 4. In the present case a four-way solenoid valve of a known type has been used. The term four-way valve is used to designate a valve in which there are two inlet and two outlet passages with valve means to alternately close and open one set of inlet and outlet passages. A three-way solenoid valve having one inlet and two outlet passages could also be employed.

A counterweight 82 is preferably provided as shown in Fig. 1 to counterbalance the weight of the motor and transmission assembly, the counterweight 82 being fastened to a rope or cable 83 which passes over pulley 84 and'is fastened to the upper member 85 at point'86.

In operation the machine is preferably electrically controlled using a suitable electric system as described in Fig. 7. The wiring diagrams illustrated in Fig. 7 comprise two circuits, namely 1l0-v0lt timer circuit and a 440-volt motor circuit. In the timer circuit, closing the spring return starter switch 87 actuates the Microfiex timer generally indicated at 88 by energizing holding magnet 89 which closes switch 90 causing the timer motor 91 to start and close micro switch 92 through a suitable cam (not shown) at a predetermined time interval, thereby energizing solenoid 93 of the air cylinder solenoid valve 81, causing the piston 76 to move downwardly along with the carriage 24 to the quenching position shown in Fig. 1. After a predetermined time interval the motor 91 opens a normally closed micro switch 94 to solenoid 93. A spring (not shown) restores solenoid valve 81 to its initial position, reversing the flow of compressed air to cylinder 75 and causing the carriage 24 to move upwardly until the supporting plate 50 occupies the dotted line position shown in Fig. 1. In this position the work piece 51 is removed and a new article to be quenched is charged onto the supporting plate 50. The timer circuit then opens. It will be understood that the solenoid valve 81 which operates the air cylinder 75 is so constructed and arranged with respect to a source of compressed air or other fluid that the carriage 24 is normally in the up-position. The distance of movement of the carriage 24 is indicated by the letter a in Fig. 1.

Simultaneously with the starting of the timer cycle, a cam (not shown) on the timer motor 91 closes a switch generally indicated by the numeral 95 in Fig. 7 thereby energizing the starter 96 to start the motor 27. The motor 27 drives shafts 30 and 31 through driving means 28 and transmission 29 in the manner previously described. The shaft 30 drives shaft 36 through gear shaft box 34, shaft 35 and gear box 37. Shaft 36 drives propeller 38 through chain and sprocket drive means 39. At the same time shaft 31 drives shaft 32 through chain and sprocket drive means 33. Shaft 32 rotates worm gear 40 which engages pinion 41 and rotates the mounting plate 50 carrying the work piece 51. i

I In the charging position shown on the right hand side of Fig. 3, the supporting plate 50 carrying the work piece 51 initially rotates horizontally about an axis substantially in a vertical plane. As the operation of the air cylinder 75 causes the carriage 24 to move downwardly the arm 7 (l pivots around the point 71 on support member 72 and causes the mounting plate 50 carrying the article to be quenched to move in an arcuate path to the quenching position shown on the left hand side of Fig. 3. Since the relationship of the driven worm gear 40 and the pinion 41 remains the same the mounting plate 50 and the article carried thereby continue to rotate but the axis of rotation shifts from a vertical plane in the charging position to a horizontal plane in the quenching position. The article 51' (Fig. 3) rotates in a substantially vertical plane about a substantially horizontal axis when in the quenching position. After a predetermined period of time, the process is reversed by the re versed actuation of the air cylinder 75 in the manner previously described causing the carriage 24 to be raised and the arm 70 to pivot upwardly around pivot point 71. The pivoting of the arm 70 upwardly around the pivot point 71 restores the axis of rotation of the support to a vertical plane as the mounting plate 50 is raised above the liquid level of the quenching bath.

The operation of the motor 27 with rotation of the supporting plate 50 is continued for a short period of time as the supporting plate 50 rises above the liquid level to cause the excess quenching medium to be thrown outwardly by centrifugal force against the sides of the tank and back into the bath. This has a wiping efiect on the quenched article and also reduces losses of the quenching medium due to dragout from the bath. The

operation of the motor 27 is then stopped by de-energizing the 440-volt circuit by a cam (not shown) on timer motor 91 opening limit switch 95. Simultaneously, the timer motor 91 is de-energized by a cam (not shown) on said timer motor, opening the 110-volt circuit through switch 90. If desired, the timer circuit and the motor circuit can be independent of each other and operated by an operator from two push button switches, one in each circuit.

The clamping member 55 is then removed from its clamping position by actuating the air cylinders 65 as previously described. This can be accomplished by manual operation of valves controlling the flow of fluids through conduits 66 and 68 or a solenoid valve and push button control system can be provided. If desired, the actuation of the clamping member can be connected with the timing cycle.

The quenched article is removed by removing the clamping member 55 in the manner described with respect to Figs. 5 and 6. A new work piece or article to be quenched is placed on support 50' and fastened thereto in the manner previously described and the operation is ready to be repeated.

The invention is especially advantageous for quenching spiral bevel gears and hypoid gears (Fig. 8). Conventional methods of quenching such gears involving placing a hot carburized gear in a press held in close die tooling under pressure and applying a controlled amount of quench oil results in gears which are loaded with internal strains and have variable amounts of distortion because of quench strains. much to be desired. Substantially improved results are obtained by the practice of the present invention.

' The machine provided in accordance with the invention is characterized by controlled temperature of the quenching bath, a controlled cycle of immersion, controlled agitation of the quenching medium, a controlled speed of rotation of the gear or other work piece being quenched and a controlled pressure on the web of the gear during the quenching operation. A particular advantage of the invention resides in the fact that the gear or other work piece can be charged horizontally and quenched vertically (i.e., while rotating on its horizontal axis). The rotation of the gear from the charging position to the quenching position is continuous. The agitation of the quenching medium is direct and provides uniform movement of the quenching medium over the gear to be quenched. The speed of the agitator can be changed by changing the setting of the gear shaft box 34-. The variable transmission 29 permits four-speed selection of the two drive shafts rotating the quench gear. Moreover, the speed of the agitator is independent of the speed of rotation of the gear and this is an important feature of the invention.

The invention is hereby claimed as follows:

1. A gear quenching machine comprising a tank adapted to have a quenching bath therein, a rotatably mounted support for supporting a hot gear to be quenched, means operatively connected with said support for moving said support into said bath to a position where the gear is completely immersed, means for rotating said gear about its axis of rotation while in said bath, and means for shifting the axis of rotation of said gear from a vertical charging position outside of said bath to a horizontal quenching position with the gear fully immersed in said bath while rotating said gear about its axis of rotation during the entire cycle of operation.

2. A gear quenching machine comprising a tank adapted to have a quenching bath therein, a rotatably mounted support for supporting a hot gear to be quenched, means operatively connected with said support for moving said support into said bath to a position where the gear is completely immersed, means for rotating said gear about its axis of rotation while in said bath, and means for shifting the axis of rotation of said gear from a vertical charging position outside of said bath to a horizontal quenching position with the gear fully immersed in said bath and back to a vertical position outside of said bath for removal of the quenched gear, all while rotating said gear about its axis of rotation.

3. A gear quenching machine comprising a tank adapted to have a quenching bath therein, a rotatably mounted support for supporting a hot gear to be quenched, means operatively connected with said support for moving said support into said bath to a position where the gear is completely immersed, means for rotating said gear about its axis of rotation while in said bath, and means responsive to movement of said support into said bath for shifting the axis of rotation of said gear from vertical to horizontal.

4. A gear quenching machine comprising a tank adapted to have a quenching bath therein, a rotatably mounted support for supporting a hot gear to be quenched, means operatively connected with said support for moving said'support into said bath to a position where the gear is completely immersed, means for rotating said gear The service life of such gears leaves about its axis of rotation while in said bath, means responsive to movement of said support into said bath for shifting the axis of rotation of said gear from vertical to horizontal and means responsive to movement of said support out of said bath for shifting said axis of rotation from horizontal to vertical.

5. In a gear quenching machine provided with a support for a hot gear to be quenched and means for moving said support into and out of a quenching bath, the combination of, means for rotatably mounting said support, means for clamping the gear on said support for rotation with the support about the axis of the gear, an agitating propeller mounted for rotation in said bath, common' drive means for rotating said propeller and said support containing said gear, and variable speed output direct drive means in the drive connection for the propeller for enabling the speed of the propeller to be varied from one preselected running speed to another.

6. In a gear quenching machine provided with a support for a hot gear to be quenched and means for moving said support into and out of a quenching bath, the combination of, means for rotatably mounting said support, means for clamping the gear on the support for rotation with the support about the axis of the gear, an agitating propeller mounted for rotation in said bath, common drive means for rotating said propeller and said support independently of each other at variable speeds when both the gear and the propeller are rotating about their axes of rotation in said bath, and variable speed output, direct drive means in the drive connection for the support for enabling the speed of the support to be varied from one preselected running speed to another.

7. A gear quenching machine comprising a tank adapted to have a quenching bath therein, a rotatably mounted support for supporting a hot gear to be quenched, means operatively connected with said support for moving said support into and out of said bath, means for rotating said support to cause the gear to rotate about its axis of rotation, means responsive to movement of said support into and out of said bath for shifting the axis of rotation of said gear from a substantially vertical position outside of said bath to a substantially horizontal position in said bath, said means for moving said gear into and out of said bath comprising a movable carriage adapted to raise and lower said support, an agitator propeller mounted from said carriage and movable therewith, said agitator propeller being located substantially directly below and in spaced relation to said rotatable support 'with the axis of rotation of said propeller substantially at right angles to the axis of rotation of said support when the axis of rotation of the support is in a horizontal plane, and motive means mounted on said carriage connected to rotate said support and said propeller at variable speeds independently of each other.

8. In a gear quenching machine utilizing a vessel adapted to contain a quenching liquid, the combination comprising a support for a hot gear to be quenched, means associated with said support for clamping the hot gear on said support, agitating means located at a spaced position directly below said gear support for agitating the quenching liquid in the direction of said gear support, means for raising and lowering said support and said agitating means while maintaining a constant spaced relationship between said support and said agitating means, power drive means, and means operatively connecting said agitating means to said power drive means and imparting agitating movement to said agitating means irrespective of the vertical positioning of the gear support and agitating means.

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